(MUNCIE) - A day-long operation to catch men and women looking for sex with an underage girl ended with four men in handcuffs.

FOX59 News reports, on Tuesday, deputies with the Delaware County Sheriff's Office received close to 400 text messages after posting an ad online on multiple escort websites.

According to court records, investigators called the undercover project "Operation Child's Play."

"Some individuals stopped texting when they found out I was only 15 years old and some continued to text," said a deputy in a probable cause affidavit.

The four arrested were:

Nathan Lee Cooper, 28, of Anderson.

Duc Hong Ta, 24, of Hamlton, Ohio.

Paul Lawrence Walker II, 38, of Muncie.

Craig Thomas Robbins, 36, of Muncie.

All four face preliminary charges of child solicitation and attempted sexual misconduct with a minor. Walker also faces one charge of attempted child exploitation. All are felony charges.

According to records, each man sent messages with the understanding that they were speaking to a girl under the age of 16, and agreed to meet at a Muncie hotel to have sex.

Instead, waiting at the hotel for the men were police deputies.

They were all arrested on Tuesday between 1:50 p.m. and 6 p.m.

Delaware County Prosecutor Eric Hoffman said the investigation into the four men's actions is still ongoing. He added his office is looking over whether or not to formally charge each person.

Sarah Hurley, the president of White Stone Project, an organization led by survivors with ties to sex trafficking who serve sexually exploited women and children, says these type of reverse stings can make a big difference in curbing the issue.

"One of the things I do like, if there is a silver lining when you read this kind of news, is I really support reverse stings," said Hurley.

According to Hurley, 2017 saw more arrests related to sex trafficking crimes than the previous eight years combined.

She hopes the crimes won't get dropped. "It was a choice on the buyer," she said. "To go online and look up a sexual transaction, and then be given age of the person involved, being a willing participant and move forward with that transaction."